 Caching first introduced in DASD CKD subsystems by Memorex (1978) and StorageTek (1981) was subsequently introduced in late 1981 by IBM on the 3880 Model 13 for models of the 3380 with dynamic pathing.The cache is dynamically managed by an algorithm; high activity data is accessed from the high-performance cache and low activity data is accessed from less-expensive DASD storage.A large memory in the Director, the cache, is divided into track slots that store data from the 3380 tracks.